Winding machine with minimum turn spacing device



B. B. SCOTT May 12, 1953 WINDING MACHINE WITH MINIMUM TURN SPACING DEVICE Filed June 18, 1949 I rwVentor: Ber-0am i n B. Scott,

VVW H is Attorney- Patented May 12, 1953 WINDINGMACHINE WITH 'runn smomegnsyrcs Benjamin B; Scott, Schenectady, N. 36., assignflz to. General Electric C New York umpany, a corporation of.

Application, June. rs, 194a. Serial No: 100,043

My invention relates to winding machinesand' more particularly to machines for winding precision variable resistance" units, and has'for its object simple and reliable'meansfor assuring a predetermined minimum-spacing between the turns of the resistance conductor.

My invention has particular application in the winding of variable resistance units with fine wire on flat card suports, which resistance units are constructed to vary the-amount of resistance in an electric circuit as an electric contactor brush is moved over bared edge portions oi the resistance turns. The resistance maybe constructed to give a resistance variation which is either a linear or non-linear function of the movement of the electric contact. In order to obtain very close limits in the predetermined linear or non-linearrelationship between resistance change and movement of the contact it is necessary that the turns be spaced apart very accurately in predetermined relative positions on the card.

Moreover, although the spacing between the turns may not be uniform and may be varied during the winding operation, it is essential that there be at least a predetermined minimum amount of spacing between turns to prevent turn GIa-ims. (or. 242,420;

short circuiting by gradual flattening of the re-- sistance wire under brushing action, to prevent turnshort circuiting because of small physical displacement: of turns under brushing action, to eliminate electrical brushing noise 'di-flicu-lti'es associated with high bond between turns arising from incomplete drying of the varnish'a pplied to secure. surface tension eifects during application of the bonding agent, and to eliminate electrical brushing noise arising from wire.- enamel on the sides of the brush edge turns following normal wear by providing mechanical clearance for brush edge cleaning to. an appropriate depth.

I- have found that the best obtainable commerical round resistance wire for use inthe manufacture of precision variable resistanceunits is: not: perfectly circular because of'manu iacturing limitations, and particularly in very fine wire, the. out of round variation assumes very perceptible proportions: such' that the wire has a pronounced tendency to roll overon a' fi at side. when a narrow edge engages the card. This rolling action, when it occurs in a direction tono ward; the. preceding turn, results in decreased. spacing; Also, microscopic machining imperfections inthe edges of card type: winding forms used in-the manufacture of precision variable v resistance units have a tendency toprod'uceadfor VariabTeResistor Winding Machine, which" ditional' wire displacement du'ri-r-ig winding operations, this condition becoming more pronounced? and of increasing importance as: wire sizes are reduced; I

In carrying out my invention in one form, I provide aspaci ng member is: interposed between the incoming wire and the preceding turn atcritical partsof the turn to assure a mini-- mum spacing, the wire being secured against rolling: actionafter the spacing member is removed: byreason oi the fact that the wireis bent around the supporting card. More specifically, I provide-a wirehaving a diameter sufiicient to provide the required. minimum spacing between the turns, wire is mounted on the resistance: wire feeding means so as to" be movable therewith and. extends in a direction perpendicular to the axis of rotation of the card and in position tin-engage the last turn at critical points on the card: and thus separate it from the turn being wound? a distance at: least as great as the predetermined required minimum spacing.

For a more complete understanding or my invention, reference should be had to the accompartying drawing, Fig; 1' of which is a fragmentary view: in perspective of a potentiometer re--' sistance winding machine embodying my invention,.whrlelilig. 2 is air-enlarged fragmentary View showingthe card in engagement with the spacing wire. I

Referring to the drawing; I have shownmy inventionin ona'form: as applied to a potentiometer resistance winding machine comprising a winding headestcch' Iflisecured to shaft. I I' and comprising. clamping jaws: t2 and I3 between is secured one end of a support or card l ke made or electricajt insulating material on which aresistance. wire: i5 is wound. The opposite end of the card M is secured by a second t6; mounted? on a shaft H in axial alignment; with the. shaiit H The card M' is showna strip of electrically insulating material hay-- ing-one straight edge, which is the electric con tact. brushing edgeof the completed resistance,

and one edgev of irregular shape provided with closed in' a: copending application of" John. R.

Moore; Serial-No; 664,471, filed April 24;, 19 16,,

guiding the wire so as to obtain the desired 1 turn spacing, a guide is provided comprising two strips, 20 and 2 I, secured together in spaced parallel relation between which the wire [5 is passed, the spacing between the strips 20 and 2| being just slightly greater than the normal diameter of the wire I5. This wire guide is preferably of the type described and claimed in my copending application Serial No. 82,112, filed March 18, 1949, for Wire Guide. The two strips 20 and 2| are carried by a carriage member 22 mounted for slidable movement in a direction parallel with the axis of rotation of the card [4. The carriage is advanced with the winding of the wire on the card in a predetermined spaced relation with the speed of the card by means of a lead screw 23 connected to the shaft ll through suitable drive gearing (not shown) indicated by the gear enclosure 24, whereby the turns are wound in a predetermined relation of minimum spacing.

In accordance with my invention, I provide positive turn spacing means comprising a wire 25 mounted on the carriage 22 and extending across and above the card M in a direction perpendicular to the axis of rotation of the card. As shown, the wire extends across two positioning pulleys 26 and 26' mounted on the carriage 22. One end of the wire is secured to a supply reel 21 mounted on the carriage 22 and secured against rotation, while its other end after passing over the guide wheel 26 extends downward in a loop and around a tension pulley 28 provided with a weight 29 and then around an adjacent pulley 30 to which it is secured. By meansof a knob 3| connected to the pulley 30 through a worm and worm wheel gearing 3|, the pulley 30 may be turned to shorten or lengthen the wire loop and thereby adjust the height of the weight 29 so that it is free to rise and fall during the winding operation without engaging the frame or other parts of the machine, whereby a predetermined. tension is maintained in the wire.

The spacing wire 25, moreover, is positioned on the carriage 22 by the pulleys 26 and 26' so as-to be engaged particularly by the brushing-edge of the card, i. e. its straight edge, as the card rotates and lie against the preceding turn as shown in Fig. 2 and thus positively space the turn 32 being wound from the preceding .turn 33 a distance 34 at least as great as the diameter of the pacing wire. It will be observed that the spacing wire extends between the incoming wire I5 and the preceding turn. Moreover, the spacing wire is of such height with respect to the card 14 that it engages the straight edge of the card preferably at approximately angular degrees of card r0- tation before the incoming wire engages the,

flat side of the card l4 and is disengaged by the card approximately degrees of card rotation.

thereafter. As the card turns under the spacing wire the card pushes the spacing wire upward at the point of engagement, the required additional length of wire being supplied from the loopby raising of the weight 29 which maintains the wire under a predetermined tension. In the event of. excessive wear of thewire 25, it is moved between.

4 the reel 21 and pulley to bring a different portion into engagement with the card. If desired, the wire 25 may be moved continuously to prevent localized wear.

Preferably, the diameter of the spacing wire 25 is selected to be approximately 15 per cent less than the design minimum spacing between any turns on the card, which spacing of turns in normal practice is approximately twice the minimum spacing required for satisfactory bonding of the resistance wire to the card by means of a suitable varnish. Ordinarily, the diameter of the spacing wire will be no greater than the diameter of the wire being wound.

It will be understood that the bending of the resistance wire l5 into a loop around the edge of the card effectively prevents rolling of the wire on the card from its wound position after the card ,disengages the spacing wire with the result that a desired minimum spacing between turns is always assured on the brushing edge of the card and generally on the sides of cards and opposite edge although this is of lesser importance.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A winding machine comprising driving means for rotating a support, wire feeding means movable by said driving means for feeding a, wire to the support so to wind the wire in spaced turns on the support, and a yieldable turn spacing member on said feeding means, means for tensioning said spacing member, said spacing member being physically oriented for interposition between the Wire and the last turn on the support for spacing each turn a predetermined distance from the preceding turn.

2. A winding machine comprising driving means for rotating a support about a predetermined axis, wire feeding means movable in substantial parallel relation with said axis, a driving connection between said feeding means and said driving means for moving said feeding means in a predetermined relation with said driving means thereby to wind a wire in spaced turns on said support, and a yieldable turn spacing member on said feeding means, means for tensioning said spacing member, said spacing member being physically oriented for interposition between the predetermined relation with said driving means thereby to wind the wire inspaced turns on said lar cross section, wire feedingmeans movable to,

vp,0ijtirrposition to be engaged by at least '0 v of thesuppcrt and lie f I and the last-turn bathe-support so as izzsgeaagass feed .a' wire to the support, a driving connection means for moving into reading means in, Pa predetermined relation with said driving means thereby to windthe wire inispaced turns. :onthe support, and a turnspacingmember on said feeding means arrangedto extend across the sipeach turn a predetermined distance from the preceding turn.

5. A winding machine comprising driving means for rotating a support about a predetermined axis, wire feeding means movable in substantially parallel relation with said axis, a driving connection between said feedin means and said driving means for moving said feeding means in a predetermined relation with said driving meansthereby to wind a wire in spaced turns on the support, and a turn spacing wire on said feeding means extending substantially at right angles with said axis for interposition between the incoming wire and the last turn on the support for spacing each turn a predetermined distance from the preceding turn.

6. A Winding machine comprising means for supporting a resistance card for rotation about a predetermined axis, means for turning said supporting means to wind a resistance wire on the card, wire feeding means movable in parallel relation with said axis, a driving connection between said feeding means and said driving means thereby to wind the wire in spaced turns on the card, and a spacing wire on said feeding means extending substantially at right angles with said axis in position to be engaged by at least one edge of the card and lie between the incoming wire and the last turn on the card so as to space each turn a predetermined distance from the preceding turn.

7. A resistance winding machine comprising driving means for supportin and rotating a flat rectangular cross section resistance card about a predetermined axis to wind a resistance wire thereon, wire feeding means movable in a direction parallel with said axis, a minimum spacing device on said feeding means comprising a spacing wire positioned for intermittent deflection by the radially outwardmost edges of the card as the card is rotated by said driving means for straddling engagement of said spacing wire by the incoming wire and the last turn on the card for maintaining a predetermined minimum spacing therebetween irrespective of the speed of movement of said wire feedin means.

8. A resistance winding machine comprising driving means for supporting and rotating a fiat rectangular cross section resistance card about a predetermined axis to wind a resistance wire thereon, wire feeding means movable in a direction parallel with said axis, means for moving said wire feeding means at a speed having a, predetermined relationship to the speed of rotation of said driving means to axially space turns of the wire on the card, a minimum spacing device on said feeding means comprising a tensioned spacing wire positioned for intermittent deflection by the radially outwardmost edges of the card as the card is rotated by said driving means for straddling engagement of said spacing wire by the incoming wire and the last turn on the card for maintaining a predetermined minimum spacing therebetween irrespective of the speed of movement of said wire feeding means.

crane resistor windingmachineoftiie time o winding a single layer of spaced turns-on a support member'and including driving means for supporting and rotating the support member about a predetermined axis-and' a wire guide movable along theaxis for establishing the spacing of the t, ns to be wound, a, minimum turn spacing I 'omprising a resilient' tensioned'member sitionedtransversely to said axis within theanlt cipated maximum radius ofrotation of the sup- "port on which the wire is to be wound mechanically connected to said guide member for axial movement therewith and having a dimension in the direction parallel to said axis corresponding to the minimum desired turn spacing.

10. A resistor winding machine comprising driving means for supporting and rotating a resistor wire support member about a predetermined axis to wind a resistance wire thereon, wire guiding means positioned beyond the maximum radius of the support to be used and movable in a direction parallel to said axis for positioning the wire as it is wound upon the support, and a spacing member for providing a minimum spacing between adjacent turns of the wire to be wound comprising a resilient spacing wire of a diameter corresponding to the minimum desired turn spacing extending transversely to said axis in a position within the maximum radius of rotation about said axis of the resistor support to be used.

11. A resistor winding machine comprising driving means for supporting and rotating a resistor Wire support memberabout a predetermined axis to wind a resistance wire thereon, wire guiding means movable in a direction parallel to said axis for positioning the wire as it is wound upon the support, a spacing member for providing a minimum spacing between adjacent turns of the wire to be wound comprising a resilient spacing wire of a diameter corresponding to the minimum desired turn spacing, supporting means for said spacing wire attached to said guiding means for movement therewith at a distance with respect to said guiding means along said axis such that the leading edge of said spacing wire is at the intended position of the following edge of the Wire being wound as it leaves said uiding means.

12. A resistor winding machine comprising driving means for supporting and rotating a resistor wire support member about a predetermined axis to wind a resistance wire thereon, wire guiding means including a guide positioned beyond the maximum radius of the support to be used and movable in a direction parallel to said axis for positioning the wire as it is wound upon the support, a spacing member for providing a minimum spacing between adjacent turns of the wire to be Wound comprising a resilient spacing wire of a diameter corresponding to the minimum desired turn spacing, means including at least one pulley wheel for supporting said spacing wire attached-to said guiding means for movement therewith, the separation of said spacing wire with respect to said guide in the direction parallel to said axis being such that the leading edge of said spacing wire is at the intended position of the following edge of the wire being wound as it leaves said guide, said spacing wire being positioned transversely to said axis and extending within the maximum radius of rotation about said axis of the resistor support to be used, and a yieldable tension means connected to said 7 space wire for applying a, tension thereto across Number said pulley wheel. 2,393,548 BENJAMIN B. SCOTT. 2,401,676 2,406,397 References Cited in the file of this patent 5 2 40 ,34

UNITED STATES PATENTS Number Name Date Number 1,627,188 Lightfoot May 3, 1927 143,624 2,360,960 Martindell Oct. 24, 1944 10 433356 2,364,696 Crom Dec. 12, 1944 Name Date McCoy Jan. 22, 1946 Weber June 4, 1946 Parkinson Aug. 2'7, 1946 Muller Sept. 3, 1946 FOREIGN PATENTS Country Date Great Britain May 25, 1920 Great Britain Apr. 19, 1938 

